Characterization of mandarin citrus germplasm from Southern Brazil by morphological and molecular analyses

The objective of this work was to characterize mandarin (Citrus spp.) germplasm from Southern Brazil by morphological and molecular analyses. Thirty seven cultivars from 34 distinct mandarin varieties were evaluated by morphological and agronomic traits of leaves, flowers and fruits, and by microsatellite markers. The morphological and agronomic characteristics suggested that almost all varieties can be produced for commercial use, and some, as the Satsuma variety, are recommended for breeding programs. Pooled DNA samples from 1-5 plants belonging to each cultivar were tested. Eight of the nine primers detected polymorphisms. Specific markers were found for some accessions. The dendrogram constructed with the morphological results divided the 37 cultivars into four groups, while that obtained with the microsatellites clustered 35 of the 37 cultivars into three groups only. Generally, intervarietal differences are not high, and this lack of agreement in the two multifactorial analyses indicates that diverse evolutionary factors are acting at these two levels of investigation.

Molecular characterization of soybean cultivars by microsatellite markers with universal tail sequence

The objective of this work was to standardize a semiautomated method for genotyping soybean, based on universal tail sequence primers (UTSP), and to compare it with the conventional genotyping method that uses electrophoresis in polyacrylamide gels. Thirty soybean cultivars were genotypically characterized by both methods, using 13 microsatellite loci. For the UTSP method, the number of alleles (NA) was 50 (2-7 per marker) and the polymorphic information content (PIC) ranged from 0.40 to 0.74. For the conventional method, the NA was 38 (2-5 per marker) and the PIC varied from 0.39 to 0.67. The genetic dissimilarity matrices obtained by the two methods were highly correlated with each other (0.8026), and the formed groups were coherent with the phenotypic data used for varietal registration. The 13 markers allowed the distinction of all analyzed cultivars. The low cost of the UTSP method, associated with its high accuracy, makes it ideal for the characterization of soybean cultivars and for the determination of genetic purity.

Modelagem Molecular: Uma Ferramenta para o Planejamento Racional de Fármacos em Química Medicinal

The molecular basis of modern therapeutics consist in the modulation of cell function by the interaction of microbioactive molecules as drug cells macromolecules structures. Molecular modeling is a computational technique developed to access the chemical structure. This methodology, by means of the molecular similarity and complementary paradigm, is the basis for the computer-assisted drug design universally employed in pharmaceutical research laboratories to obtain more efficient, more selective, and safer drugs. In this work, we discuss some methods for molecular modeling and some approaches to evaluate new bioactive structures in development by our research group.

Discrepancies over the onset of surfactant monomer aggregation interpreted by fluorescence, conductivity and surface tension methods

Molecular probe techniques have made important contributions to the determination of microstructure of surfactant assemblies such as size, stability, micropolarity and conformation. Conductivity and surface tension were used to determine the critical aggregation concentration (cac) of polymer-surfactant complexes and the critical micellar concentration (cmc) of aqueous micellar aggregates. The results are compared with those of fluorescent techniques. Several surfactant systems were examined, 1-butanol-sodium dodecylsulfate (SDS) mixtures, solutions containing poly(ethylene oxide)-SDS, poly(vinylpyrrolidone)-SDS and poly(acrylic acid)-alkyltrimethylammonium bromide complexes. We found differences between the cac and cmc values obtained by conductivity or surface tension and those obtained by techniques which use hydrophobic probe.

Análise multicomponente simultânea por espectrofotometria de absorção molecular UV-VIS

This review presents the evolution of simultaneous multicomponent analysis by absorption spectrophotometry in the ultraviolet and visual regions in terms of some qualitative and quantitative analysis techniques, otimization methods, as well as applications and modern trends.

Entendendo estrutura molecular com a molécula de hidrogênio ionizada

In this paper a general view about the modern molecular structure theory is developed discussing the ionized hydrogen molecule. We introduce some necessary approximation methods for the electronic and nuclear spectra study adopting a systematic approach. In addition though, we have performed calculations in order to illustrate these methods.

Determinação da estrutura molecular do ciclooctano por métodos ab initio e difração de elétrons na fase gasosa

The determination of the molecular structure of molecules is of fundamental importance in chemistry. X-rays and electron diffraction methods constitute in important tools for the elucidation of the molecular structure of systems in the solid state and gas phase, respectively. The use of quantum mechanical molecular orbital ab initio methods offer an alternative for conformational analysis studies. Comparison between theoretical results and those obtained experimentally in the gas phase can make a significant contribution for an unambiguous determination of the geometrical parameters. In this article the determination of the molecular structure of the cyclooctane molecule by electron diffraction in the gas phase and ab initio calculations will be addressed, providing an example of a comparative analysis of theoretical and experimental predictions.

Economia de átomos, engenharia molecular e catálise organometálica bifásica: conceitos moleculares para tecnologias limpas

For economical and ecological reasons, synthetic chemists are confronted with the increasing obligation of optimizing their synthetic methods. Maximizing efficiency and minimizing costs in the production of molecules and macromolecules constitutes, therefore, one of the most exciting challenges of synthetic chemistry. The ideal synthesis should produce the desired product in 100% yield and selectivity, in a safe and environmentally acceptable process. In this highlight the concepts of atom economy, molecular engineering and biphasic organometallic catalysis, which address these issues at the molecular level for the generation of "green" technologies, are introduced and discussed.

Metodologia para obtenção de parâmetros de mecânica molecular aplicados a compostos de coordenação

A methodology is presented to obtain force field parameters to be used in molecular mechanics. The case of Ru(II) is investigated and the parameters obtained, specially its covalent radii, are employed to model Ru(II) coordination compound. The combined use of molecular mechanics with ab initio methods allowed us to predict the metal-ligand stretching force constant for Ru(II) coordination compounds.

Introdução a modelagem molecular de fármacos no curso experimental de química farmacêutica

Molecular Modeling is an important tool in drug design and it is very useful to predict biological activity from a library of compounds. A wide variety of computer programs and methods have been developed to visualize the tridimensional geometry and calculate physical properties of drugs. In this work, we describe a practical approach of molecular modeling as a powerful tool to study structure-activity relationships of drugs, including some antibacterials, hormones, cholinergic and adrenergic agents. At first, the students learn how to draw 3D structures and use them to perform conformational and molecular analysis. Thus, they compare drugs with similar pharmacological activity by superimposing one structure on the top of another and evaluate the geometry and physical properties.

Vanadium-modified molecular sieves: preparation, characterization and catalysis

Vanadium-containing molecular sieves are redox catalysts and are good candidates as substitutes for oxide-supported V2O5 in a number of reactions. These materials have the advantage of presenting better dispersion of vanadium species, as well as shape-selective properties and controllable acidities. They may be prepared by one-pot synthesis or by post-synthesis methods and a number of techniques such as diffuse reflectance UV-visible spectroscopy, 51V nuclear magnetic resonance and electron paramagnetic resonance, to name but a few, have been used to characterize these materials. In this review, methods of preparation of vanadium-modified molecular sieves, their characterization and applications in catalysis are discussed.

Polímeros com capacidade de reconhecimento molecular no controlo da libertação de fármacos. Parte 1: síntese e caracterização

Molecularly imprinted polymers (MIPs) consist of synthetic macromolecular matrix, obtained through molecular imprinting-based methods that show ability to selectively recognize important biological molecules and its application in the drug delivery field is under development. In the present review the main aspects related to the synthesis and characterization of MIPs are studied. The fundamental variables participating in the synthesis process, such as template molecule, functional monomers, cross-linking agents, solvents and imprinting approaches are discussed. Moreover, the main available methods for MIPs chemical and morphological characterization are presented and the importance of the obtained information is discussed.

Termocromismo em soluções de alcóxidos de Vanádio(IV): uma abordagem pela modelagem molecular

The thermochromic behavior exhibited by vanadium(IV) alkoxides, [V2(μ-OPr i)2(OPr i) 6] and [V2(μ-ONep)2(ONep)6 ], OPr i = isopropoxide and ONep = neopentoxide, was studied by molecular modeling using DFT, TDDFT and INDO/S methods. The vibrational and electronic spectra calculated for [V2(μ-OPr i)2(OPr i) 6] were very similar to the experimental data registered for crystalline samples of the complex and for its solutions at low temperature (< 210 K), while spectra recorded at high temperature (> 315 K) were compatible with those calculated for the monomeric form, [V(OPr i)4]. These results consistently point to a monomer/dimer equilibrium as an explanation for the solution thermochromism of {V(OPr i)4}n. In spite of the structural similarity between [V2(μ-ONep)2(ONep)6 ] and [V2(μ-OPr i)2(OPr i) 6] in the solid state, the thermochromic behavior of the former could not be explained by the same model, and the possibility of tetranuclear aggregation at low temperatures was also investigated.

Efficient synthesis of sulfonamide derivatives on solid supports catalyzed using solvent-free and microwave-assisted methods

In this work we report the synthesis of sulfonamide derivatives using a conventional procedure and with solid supports, such as silica gel, florisil, alumina, 4Å molecular sieves, montmorillonite KSF, and montmorillonite K10 using solvent-free and microwave-assisted methods. Our results show that solid supports have a catalytic activity in the formation of sulfonamide derivatives. We found that florisil, montmorillonite KSF, and K10 could be used as inexpensive alternative catalysts that are easily separated from the reaction media. Additionally, solvent-free and microwave-assisted methods were more efficient in reducing reaction time and in increasing yield.

DISCRIMINAÇÃO DE MADEIRAS SIMILARES POR FLUORESCÊNCIA MOLECULAR E MÍNIMOS QUADRADOS PARCIAIS

Wood is an extremely complex biological material, which can show macroscopic similarities that make it difficult to discriminate between species. Discrimination between similar wood species can be achieved by either anatomic or instrumental methods, such as near infrared spectroscopy (NIR). Although different spectroscopy methods are currently available, few studies have applied them to discriminate between wood species. In this study, we applied a partial least squares-discriminant analysis (PLS-DA) model to evaluate the viability of using direct fluorescence measurements for discriminating between Eucalyptus grandis, Eucalyptus urograndis, and Cedrela odorata. The results show that molecular fluorescence is an efficient technique for discriminating between these visually similar wood species. With respect to calibration and the validation samples, we observed no misclassifications or outliers.